A factory welder is tasked with performing a root pass on a 6 mm thick mild steel plate in the horizontal (2G) position using SMAW. They are using an E6010 electrode, DCEN polarity, and an amperage setting in the middle of the electrode's recommended range. The resulting root pass shows inconsistent penetration, with some areas exhibiting burn-through and others lacking fusion. What is the most likely cause of these inconsistent results?

Question: A factory welder is tasked with performing a root pass on a 6 mm thick mild steel plate in the horizontal (2G) position using SMAW. They are using an E6010 electrode, DCEN polarity, and an amperage setting in the middle of the electrode's recommended range. The resulting root pass shows inconsistent penetration, with some areas exhibiting burn-through and others lacking fusion. What is the most likely cause of these inconsistent results?

Answer options: ✅ Incorrect electrode manipulation causing uneven heat distribution

• The electrode's specific coating is unsuitable for horizontal roots
• Excessive open-circuit voltage from the power source
• Insufficient preheat applied to the joint

Correct answer: Incorrect electrode manipulation causing uneven heat distribution

Explanation: Inconsistent penetration with an E6010 root pass, especially showing both burn-through and lack of fusion, strongly suggests inconsistent electrode manipulation. This leads to varying arc length, travel speed, and heat input, which directly impacts penetration. E6010 on DCEN is suitable for horizontal roots, open-circuit voltage isn't typically the cause of inconsistent penetration in this way, and insufficient preheat would usually result in consistent lack of fusion, not burn-through.